DATASHEET
Raspberry Pi Compute Module (CM1)
Raspberry Pi Compute Module 3 (CM3)
Raspberry Pi Compute Module 3 Lite (CM3L)
Version 1.0, October 2016
Copyright 2016 Raspberry Pi (Trading) Ltd. All rights reserved.
Copyright Raspberry Pi (Trading) Ltd. 2016
Table 1: Revision History
Revision Date Description
1.0 13/10/2016 First release
Compute Module Datasheet
1 Version 1.0
Compute Module Datasheet
Copyright Raspberry Pi (Trading) Ltd. 2016
Contents
1 Introduction 5
2 Features 6
2.1 Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Peripherals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3 Block Diagram 7
4 Mechanical Specification 9
5 Pin Assignments 11
6 Electrical Specification 13
7 Power Supplies 14
7.1 Supply Sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.2 Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
8 Booting 16
9 Peripherals 17
9.1 GPIO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
9.1.1 GPIO Alternate Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
9.1.2 Secondary Memory Interface (SMI) . . . . . . . . . . . . . . . . . . . . . . . . 19
9.1.3 Display Parallel Interface (DPI) . . . . . . . . . . . . . . . . . . . . . . . . . . 19
9.1.4 SD/SDIO Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
9.2 CSI (MIPI Serial Camera) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
9.3 DSI (MIPI Serial Display) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
9.4 USB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
9.5 HDMI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
9.6 Composite (TV Out) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
10 Thermals 21
10.1 Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
11 Availability 21
12 Support 21
2 Version 1.0
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List of Figures
1 CM1 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 CM3/CM3L Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3 CM1 Mechanical Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4 CM3 and CM3L Mechanical Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . 10
5 Digital IO Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3 Version 1.0
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List of Tables
1 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Compute Module SODIMM Connector Pinout . . . . . . . . . . . . . . . . . . . . . . . 11
3 Pin Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5 DC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6 Digital I/O Pin AC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7 Power Supply Operating Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
8 Mimimum Power Supply Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . 16
9 GPIO Bank0 Alternate Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
10 GPIO Bank1 Alternate Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4 Version 1.0
Compute Module Datasheet
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1 Introduction
The Raspberry Pi Compute Module (CM1), Compute Module 3 (CM3) and Compute Module 3 Lite
(CM3L) are DDR2-SODIMM-mechanically-compatible System on Modules (SoMs) containing processor, memory, eMMC Flash (for CM1 and CM3) and supporting power circuitry. These modules
allow a designer to leverage the Raspberry Pi hardware and software stack in their own custom systems
and form factors. In addition these module have extra IO interfaces over and above what is available on
the Raspberry Pi model A/B boards opening up more options for the designer.
The CM1 contains a BCM2835 processor (as used on the original Raspberry Pi and Raspberry Pi B+
models), 512MByte LPDDR2 RAM and 4Gbytes eMMC Flash. The CM3 contains a BCM2837 processor (as used on the Raspberry Pi 3), 1Gbyte LPDDR2 RAM and 4Gbytes eMMC Flash. Finally the
CM3L product is the same as CM3 except the eMMC Flash is not fitted, and the SD/eMMC interface
pins are available for the user to connect their own SD/eMMC device.
Note that the BCM2837 processor is an evolution of the BCM2835 processor. The only real differences
are that the BCM2837 can address more RAM (up to 1Gbyte) and the ARM CPU complex has been
upgraded from a single core ARM11 in BCM2835 to a Quad core Cortex A53 with dedicated 512Kbyte
L2 cache in BCM2837. All IO interfaces and peripherals stay the same and hence the two chips are
largely software and hardware compatible.
The pinout of CM1 and CM3 are identical. Apart from the CPU upgrade and increase in RAM the
other significant hwardware differences to be aware of are that CM3 has grown from 30mm to 31mm
in height, the VBAT supply can now draw significantly more power under heavy CPU load, and the
HDMI HPD N 1V8 (GPIO46 1V8 on CM1) and EMMC EN N 1V8 (GPIO47 1V8 on CM1) are now
driven from an IO expander rather than the processor. If a designer of a CM1 product has a suitably
specified VBAT, can accomodate the extra 1mm module height increase and has followed the design
rules with respect to GPIO46 1V8 and GPIO47 1V8 then a CM3 should work fine in a board designed
for a CM1.
5 Version 1.0
2 Features
2.1 Hardware
• Low cost
• Low power
• High availability
• High reliability
– Tested over millions of Raspberry Pis Produced to date
– Module IO pins have 35u hard gold plating
2.2 Peripherals
• 48x GPIO
Compute Module Datasheet
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• 2x I2C
• 2x SPI
• 2x UART
• 2x SD/SDIO
• 1x HDMI 1.3a
• 1x USB2 HOST/OTG
• 1x DPI (Parallel RGB Display)
• 1x NAND interface (SMI)
• 1x 4-lane CSI Camera Interface (up to 1Gbps per lane)
• 1x 2-lane CSI Camera Interface (up to 1Gbps per lane)
• 1x 4-lane DSI Display Interface (up to 1Gbps per lane)
• 1x 2-lane DSI Display Interface (up to 1Gbps per lane)
2.3 Software
• ARMv6 (CM1) or ARMv7 (CM3, CM3L) Instruction Set
• Mature and stable Linux software stack
– Latest Linux Kernel support
– Many drivers upstreamed
– Stable and well supported userland
– Full availability of GPU functions using standard APIs
6 Version 1.0
3 Block Diagram
512MByte
LPDDR2
200 Pin SODIMM Connector
Core SMPS
GPIO[0:27]
VDD_GPIO0-27
GPIO[28:45]
VDD_GPIO28-45
VBAT
3V3
1V8
VDAC
4GByte eMMC
TVDAC
CSI CAM0
CSI CAM1
2 Lane CSI Camera
4 Lane CSI Camera
BCM2835
DSI DISP0
DSI DISP1
2 Lane DSI Display
4 Lane DSI Display
HDMI TMDS
CLOCK & DATA
CM
CHOKES
RUN
HDMI CEC, DDC
HDMI_HPD_N_1V8 (GPIO46_1V8)
EMMC_EN_N_1V8 (GPIO47_1V8)
JTAG
EMMC_DISABLE_N
USB
USB2
USB_OTGID
HDMI CEC & I2C
3V3
RUN
TV
DAC
GPIO
BANK0
GPIO
BANK1
3V3
SD_CLK
SD_CMD, Dx
SD I/O VOLTAGE
1V8
eMMC I/O
Voltage fixed at
1V8
Compute Module Datasheet
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Figure 1: CM1 Block Diagram
7 Version 1.0
1GByte LPDDR2
200 Pin SODIMM Connecto r
IO Expander
Core SMPS
GPIO[0:27]
VDD_GPIO0-27
GPIO[28:45]
VDD_GPIO28-45
VBAT
3V3
1V8
VDAC
4GByte eMMC
(CM3 only)
TVDAC
CSI CAM0
CSI CAM1
2 Lane CSI Camera
4 Lane CSI Camera
BCM2837
DSI DISP0
DSI DISP1
2 Lane DSI Display
4 Lane DSI Display
HDMI TMDS
CLOCK & DATA
CM
CHOKES
RUN
HDMI CEC, DDC
HDMI_HPD_N_1V8
EMMC_EN_N_1V8
JTAG
EMMC_DISABLE_N
USB
USB2
USB_OTGID
HDMI CEC & I2C
SDX_CMD, Dx (CM3 Lite only)
SDX_CLK (CM3 Lite only)
3V3
RUN
TV
DAC
GPIO
BANK0
GPIO
BANK1
3V3
SD_CLK
SD_CMD, Dx
SDX_VDD (CM3 Lite only)
SD I/O VOLTAGE
1V8
CM3 eMMC I/O
Voltage fixed at
1V8
CM3-Lite SD I/O
Voltage supplied
from SDX_VDD
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Figure 2: CM3/CM3L Block Diagram
8 Version 1.0
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4 Mechanical Specification
The Compute Modules conform to JEDEC MO-224 mechanical specification for 200 pin DDR2 (1.8V)
SODIMM modules (with the exception that the CM3, CM3L modules are 31mm in height rather than
30mm of CM1) and therefore should work with the many DDR2 SODIMM sockets available on the
market. (Please note that the pinout of the Compute Module is not the same as a DDR2 SODIMM
module; they are not electrically compatible.)
The SODIMM form factor was chosen as a way to provide the 200 pin connections using a standard,
readily available and low cost connector compatible with low cost PCB manufacture.
The maximum component height on the underside of the Compute Module is 1.2mm.
The maximum component height on the top side of the Compute Module is 1.5mm.
The Compute Module PCB thickness is 1.0mm +/- 0.1mm.
Note that the location and arrangement of components on the Compute Module may change slightly
over time due to revisions for cost and manufacturing considerations; however, maximum component
heights and PCB thickness will be kept as specified.
Figure 3 gives the CM1 mechanical dimensions. Figure 4 gives the CM3 and CM3L mechanical dimensions.
Figure 3: CM1 Mechanical Dimensions
9 Version 1.0
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Figure 4: CM3 and CM3L Mechanical Dimensions
10 Version 1.0
5 Pin Assignments
CM1
CM3-Lite
CM3
PIN
PIN
CM3
CM3-Lite
CM1
1
2
34NC
SDX_VDD
NC
56NC
SDX_VDD
NC
78NC
910NC
SDX_CLK
NC
1112NC
SDX_CMD
NC
1314NC
1516NC
SDX_D0
NC
1718NC
SDX_D1
NC
1920NC
2122NC
SDX_D2
NC
2324NC
SDX_D3
NC
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
8788GPIO46_1V8
8990GPIO47_1V8
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
3V3
3V3
GND
VBAT
VBAT
HDMI_HPD_N_1V8
EMMC_EN_N_1V8
VDD_CORE (DO NOT CONNECT)
GND
1V8
1V8
GND
VDAC
USB_DM
GND
HDMI_CEC
HDMI_SDA
HDMI_SCL
RUN
CAM1_DN1
GND
CAM1_DP0
CAM1_DN0
GND
USB_DP
CAM1_DN2
GND
CAM1_CP
CAM1_CN
GND
CAM1_DP1
HDMI_D2_P
GND
CAM1_DP3
CAM1_DN3
GND
CAM1_DP2
HDMI_D0_P
GND
HDMI_D1_N
HDMI_D1_P
GND
HDMI_D2_N
DSI0_CP
GND
HDMI_CLK_N
HDMI_CLK_P
GND
HDMI_D0_N
DSI0_DP1
GND
DSI0_DN0
DSI0_DP0
GND
DSI0_CN
GPIO25
GND
GPIO26
GPIO27
GND
DSI0_DN1
GPIO21
GND
GPIO22
GPIO23
GND
GPIO24
GPIO17
GND
GPIO18
GPIO19
GND
GPIO20
GPIO13
GND
GPIO14
GPIO15
GND
GPIO16
GND
GPIO0-27_VDD
GPIO28-45_VDD
GND
GPIO12
GND
GPIO8
GPIO9
GND
GPIO10
GPIO11
GND
GPIO4
GPIO5
GND
GPIO6
GPIO7
GND
GPIO0
GPIO1
GND
GPIO2
GPIO3
VDAC
3V3
3V3
GND
VBAT
VBAT
VC_TDO
VC_TCK
GND
1V8
1V8
GND
TVDAC
USB_OTGID
GND
VC_TRST_N
VC_TDI
VC_TMS
NC
NC
NC
NC
NC
GND
CAM0_CP
CAM0_CN
GND
CAM0_DP1
CAM0_DN1
GND
NC
NC
GND
CAM0_DP0
CAM0_DN0
GND
DSI1_DP1
DSI1_DN1
GND
NC
NC
NC
DSI1_DP3
DSI1_DN3
GND
DSI1_DP2
DSI1_DN2
GND
DSI1_DP0
DSI1_DN0
GND
DSI1_CP
DSI1_CN
GND
GPIO44
GPIO45
GND
GND
GPIO40
GPIO41
GND
GPIO42
GPIO43
GND
GPIO36
GPIO37
GND
GPIO38
GPIO39
GND
GPIO32
GPIO33
GND
GPIO34
GPIO35
GND
GPIO30
GPIO31
GND
GPIO0-27_VDD
GPIO28-45_VDD
GND
KEY
EMMC_DISABLE_N
GND
GND
GND
GND
GPIO28
GPIO29
GND
Compute Module Datasheet
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Table 2 gives the Compute Module pinout and Table 3 gives the Compute Module pin functions.
Table 2: Compute Module SODIMM Connector Pinout
11 Version 1.0
Compute Module Datasheet
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Pin Name DIR Voltage Ref PDNaState If Unused Description/Notes
RUN and Boot Control (see text for usage guide)
RUN I 3V3
EMMC DISABLE N I 3V3
EMMC EN N 1V8 O 1V8 Pull High Leave open Has internal 2k2 pull up
GPIO
GPIO[27:0] I/O GPIO0-27 VDD Pull or Hi-ZcLeave open GPIO Bank 0
GPIO[45:28] I/O GPIO28-45 VDD Pull or Hi-ZcLeave open GPIO Bank 1
Primary SD Interface
d,e
SDX CLK O SDX VDD Pull High Leave open Primary SD interface CLK
SDX CMD I/O SDX VDD Pull High Leave open Primary SD interface CMD
SDX Dx I/O SDX VDD Pull High Leave open Primary SD interface DATA
USB Interface
USB Dx I/O - Z Leave open Serial interface
USB OTGID I 3V3 Tie to GND OTG pin detect
HDMI Interface
HDMI SCL I/O 3V3
HDMI SDA I/O 3V3
HDMI CEC I/O 3V3 Z Leave open CEC (has internal 27k pull up)
HDMI CLKx O - Z Leave open HDMI serial clock
HDMI Dx O - Z Leave open HDMI serial data
HDMI HPD N 1V8 I 1V8 Pull High Leave open HDMI hotplug detect
CAM0 (CSI0) 2-lane Interface
CAM0 Cx I - Z Leave open Serial clock
CAM0 Dx I - Z Leave open Serial data
CAM1 (CSI1) 4-lane Interface
CAM1 Cx I - Z Leave open Serial clock
CAM1 Dx I - Z Leave open Serial data
DSI0 (Display 0) 2-lane Interface
DSI0 Cx O - Z Leave open Serial clock
DSI0 Dx O - Z Leave open Serial data
DSI1 (Display 1) 4-lane Interface
DSI1 Cx O - Z Leave open Serial clock
DSI1 Dx O - Z Leave open Serial data
TV Out
TVDAC O - Z Leave open Composite video DAC output
JTAG Interface
TMS I 3V3 Z Leave open Has internal 50k pull up
TRST N I 3V3 Z Leave open Has internal 50k pull up
TCK I 3V3 Z Leave open Has internal 50k pull up
TDI I 3V3 Z Leave open Has internal 50k pull up
TDO O 3V3 O Leave open Has internal 50k pull up
a
The PDN column indicates power-down state (when RUN pin LOW)
b
Must be driven by an open-collector driver
c
GPIO have software enabled pulls which keep state over power-down
d
Only available on Lite variants
e
The CM will always try to boot from this interface first
f
Requires external pull-up resistor to 5V as per HDMI spec
b
b
b
b
Pull High Leave open Has internal 10k pull up
Pull High Leave open Has internal 10k pull up
f
Z
f
Z
Leave open DDC Clock (5.5V tolerant)
Leave open DDC Data (5.5V tolerant)
Table 3: Pin Functions
12 Version 1.0
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6 Electrical Specification
Caution! Stresses above those listed in Table 4 may cause permanent damage to the device. This is
a stress rating only; functional operation of the device under these or any other conditions above those
listed in the operational sections of this specification is not implied. Exposure to absolute maximum
rating conditions for extended periods may affect device reliability.
Symbol Parameter Minimum Maximum Unit
VBAT Core SMPS Supply -0.5 6.0 V
3V3 3V3 Supply Voltage -0.5 4.10 V
1V8 1V8 Supply Voltage -0.5 2.10 V
VDAC TV DAC Supply -0.5 4.10 V
GPIO0-27 VDD GPIO0-27 I/O Supply Voltage -0.5 4.10 V
GPIO28-45 VDD GPIO28-27 I/O Supply Voltage -0.5 4.10 V
SDX VDD Primary SD/eMMC Supply Voltage -0.5 4.10 V
Table 4: Absolute Maximum Ratings
DC Characteristics are defined in Table 5
Symbol Parameter Conditions Minimum Typical Maximum Unit
V
V
I
C
V
V
I
I
IL
IH
IL
IN
OL
OH
OL
OH
Input low voltage
Input high voltage
Input leakage current TA = +85◦C - - 5 µA
Input capacitance - - 5 - pF
Output low voltagebVDD IO = 1.8V, IOL = -2mA - - 0.2 V
Output high voltagebVDD IO = 1.8V, IOH = 2mA 1.6 - - V
Output low currentcVDD IO = 1.8V, VO = 0.4V 12 - - mA
Output high currentcVDD IO = 1.8V, VO = 1.4V 10 - - mA
a
VDD IO = 1.8V - - 0.6 V
VDD IO = 2.7V - - 0.8 V
a
VDD IO = 1.8V 1.0 - - V
VDD IO = 2.7V 1.3 - - V
VDD IO = 2.7V, IOL = -2mA - - 0.15 V
VDD IO = 2.7V, IOH = 2mA 2.5 - - V
VDD IO = 2.7V, VO = 0.4V 17 - - mA
VDD IO = 2.7V, VO = 2.3V 16 - - mA
R
P U
R
P D
a
Hysteresis enabled
b
Default drive strength (8mA)
c
Maximum drive strength (16mA)
Pullup resistor - 50 - 65 kΩ
Pulldown resistor - 50 - 65 kΩ
Table 5: DC Characteristics
13 Version 1.0
Compute Module Datasheet
t
fall
t
rise
DIGITAL
OUTPUT
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AC Characteristics are defined in Table 6 and Fig. 5.
Pin Name Symbol Parameter Minimum Typical Maximum Unit
Digital outputs t
Digital outputs t
rise
fall
10-90% rise time
90-10% fall time
a
a
- 1.6 - ns
- 1.7 - ns
GPCLK t
JOSC
Oscillator-derived GPCLK - - 20 ps
cycle-cycle jitter (RMS)
GPCLK t
JP LL
PLL-derived GPCLK - - 48 ps
cycle-cycle jitter (RMS)
a
Default drive strength, CL = 5pF, VDD IOx = 3.3V
Table 6: Digital I/O Pin AC Characteristics
Figure 5: Digital IO Characteristics
7 Power Supplies
The Compute Module has six separate supplies that must be present and powered at all times; you cannot
leave any of them unpowered, even if a specific interface or GPIO bank is unused. The six supplies are
as follows:
1. VBAT is used to power the BCM283x processor core. It feeds the SMPS that generates the chip
core voltage.
2. 3V3 powers various BCM283x PHYs, IO and the eMMC Flash.
3. 1V8 powers various BCM283x PHYs, IO and SDRAM.
4. VDAC powers the composite (TV-out) DAC.
5. GPIO0-27 VREF powers the GPIO 0-27 IO bank.
6. GPIO28-45 VREF powers the GPIO 28-45 IO bank.
14 Version 1.0
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Supply Descripion Minimum Typical Maximum Unit
VBAT Core SMPS Supply 2.5 - 5.0 + 5% V
3V3 3V3 Supply Voltage 3.3 - 5% 3.3 3.3 + 5% V
1V8 1V8 Supply Voltage 1.8 - 5% 1.8 1.8 + 5% V
VDAC TV DAC Supply
a
2.5 - 5% 2.8 3.3 + 5% V
GPIO0-27 VDD GPIO0-27 I/O Supply Voltage 1.8 - 5% - 3.3 + 5% V
GPIO28-45 VDD GPIO28-27 I/O Supply Voltage 1.8 - 5% - 3.3 + 5% V
SDX VDD Primary SD/eMMC Supply Voltage 1.8 - 5% - 3.3 + 5% V
a
Requires a clean 2.5-2.8V supply if TV DAC is used, else connect to 3V3
Table 7: Power Supply Operating Ranges
7.1 Supply Sequencing
Supplies should be staggered so that the highest voltage comes up first, then the remaining voltages
in descending order. This is to avoid forward biasing internal (on-chip) diodes between supplies, and
causing latch-up. Alternatively supplies can be synchronised to come up at exactly the same time as
long as at no point a lower voltage supply rail voltage exceeds a higher voltage supply rail voltage.
7.2 Power Requirements
Exact power requirements will be heavily dependent upon the individual use case. If an on-chip subsystem is unused, it is usually in a low power state or completely turned off. For instance, if your application
does not use 3D graphics then a large part of the core digital logic will never turn on and need power.
This is also the case for camera and display interfaces, HDMI, USB interfaces, video encoders and
decoders, and so on.
Powerchain design is critical for stable and reliable operation of the Compute Module. We strongly
recommend that designers spend time measuring and verifying power requirements for their particular
use case and application, as well as paying careful attention to power supply sequencing and maximum
supply voltage tolerance.
Table 8 specifies the recommneded minimum power supply outputs required to power the Compute
Module.
15 Version 1.0
Compute Module Datasheet
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Supply Minimum Requirement Unit
VBAT (CM1) 2000
VBAT (CM3,3L) 3500
a
a
mW
mW
3V3 250 mA
1V8 250 mA
VDAC 25 mA
GPIO0-27 VDD 50
GPIO28-45 VDD 50
SDX VDD 50
a
Recommended minimum. Actual power drawn is very dependent on use-case
b
Each GPIO can supply up to 16mA, aggregate current per bank must not exceed 50mA
b
b
b
mA
mA
mA
Table 8: Mimimum Power Supply Requirements
8 Booting
The 4GB eMMC Flash device on CM3 is directly connected to the primary BCM2837 SD/eMMC interface. These connections are not accessible on the module pins. On CM3L this SD interface is available
on the SDX pins.
When initially powered on, or after the RUN pin has been held low and then released, the BCM2837
will try to access the primary SD/eMMC interface. It will then look for a file called bootcode.bin on the
primary partition (which must be FAT) to start booting the system. If it cannot access the SD/eMMC
device or the boot code cannot be found, it will fall back to waiting for boot code to be written to it over
USB; in other words, its USB port is in slave mode waiting to accept boot code from a suitable host.
A USB boot tool is available on Github which allows a host PC running Linux to write the BCM2837
boot code over USB to the module. That boot code then runs and provides access to the SD/eMMC as a
USB mass storage device, which can then be read and written using the host PC. Note that a Raspberry Pi
can be used as the host machine. For those using Windows a precompiled and packeged tool is available.
For more information see here.
The Compute Module has a pin called EMMC DISABLE N which when shorted to GND will disable
the SD/eMMC interface (by physically disconnecting the SD CMD pin), forcing BCM2837 to boot from
USB. Note that when the eMMC is disabled in this way, it takes a couple of seconds from powering up
for the processor to stop attempting to talk to the SD/eMMC device and fall back to booting from USB.
Note that once booted over USB, BCM2837 needs to re-enable the SD/eMMC device (by releasing
EMMC DISABLE N) to allow access to it as mass storage. It expects to be able to do this by driving
the EMMC EN N 1V8 pin LOW, which at boot is initially an input with a pull up to 1V8. If an end user
wishes to add the ability to access the SD/eMMC over USB in their product, similar circuitry to that
used on the Compute Module IO Board to enable/disable the USB boot and SD/eMMC must be used;
that is, EMMC DISABLE N pulled low via MOSFET(s) and released again by MOSFET, with the gate
controlled by EMMC EN N 1V8. Ensure you use MOSFETs suitable for switching at 1.8V (i.e. use a
device with gate threshold voltage, Vt, suitable for 1.8V switching).
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9 Peripherals
9.1 GPIO
BCM283x has in total 54 GPIO lines in 3 separate voltage banks. All GPIO pins have at least two
alternative functions within the SoC. When not used for the alternate peripheral function, each GPIO
pin may be set as an input (optionally as an interrupt) or an output. The alternate functions are usually
peripheral I/Os, and most peripherals appear twice to allow flexibility on the choice of I/O voltage.
On CM1, CM3 and CM3L bank2 is used on the module to connect to the eMMC device and, on CM3
and CM3L, for an on-board I2C bus (to talk to the core SMPS and control the special function pins). On
CM3L most of bank 2 is exposed to allow a user to connect their choice of SD card or eMMC device (if
required).
Bank0 and 1 GPIOs are available for general use. GPIO0 to GPIO27 are bank 0 and GPIO28-45 make
up bank1. GPIO0-27 VDD is the power supply for bank0 and GPIO28-45 VDD is the power supply for
bank1. SDX VDD is the supply for bank2 on CM3L. These supplies can be in the range 1.8V-3.3V (see
Table 7) and are not optional; each bank must be powered, even when none of the GPIOs for that bank
are used.
Note that the HDMI HPD N 1V8 and EMMC EN N 1V8 pins (on CM1 these were called GPIO46 1V8
and GPIO47 1V8 respectively) are 1.8V IO and are used for special functions (HDMI hot plug detect and boot control respectively). Please do not use these pins for any other purpose, as the
software for the Compute Module will always expect these pins to have these special functions. If
they are unused please leave them unconnected.
All GPIOs except GPIO28, 29, 44 and 45 have weak in-pad pull-ups or pull-downs enabled when the
device is powered on. It is recommended to add off-chip pulls to GPIO28, 29, 44 and 45 to make sure
they never float during power on and initial boot.
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9.1.1 GPIO Alternate Functions
Default
GPIO Pull ALT0 ALT1 ALT2 ALT3 ALT4 ALT5
0 High SDA0 SA5 PCLK - - -
1 High SCL0 SA4 DE - - -
2 High SDA1 SA3 LCD VSYNC - - -
3 High SCL1 SA2 LCD HSYNC - - -
4 High GPCLK0 SA1 DPI D0 - - ARM TDI
5 High GPCLK1 SA0 DPI D1 - - ARM TDO
6 High GPCLK2 SOE N DPI D2 - - ARM RTCK
7 High SPI0 CE1 N SWE N DPI D3 - - -
8 High SPI0 CE0 N SD0 DPI D4 - - -
9 Low SPI0 MISO SD1 DPI D5 - - -
10 Low SPI0 MOSI SD2 DPI D6 - - -
11 Low SPI0 SCLK SD3 DPI D7 - - -
12 Low PWM0 SD4 DPI D8 - - ARM TMS
13 Low PWM1 SD5 DPI D9 - - ARM TCK
14 Low TXD0 SD6 DPI D10 - - TXD1
15 Low RXD0 SD7 DPI D11 - - RXD1
16 Low FL0 SD8 DPI D12 CTS0 SPI1 CE2 N CTS1
17 Low FL1 SD9 DPI D13 RTS0 SPI1 CE1 N RTS1
18 Low PCM CLK SD10 DPI D14 - SPI1 CE0 N PWM0
19 Low PCM FS SD11 DPI D15 - SPI1 MISO PWM1
20 Low PCM DIN SD12 DPI D16 - SPI1 MOSI GPCLK0
21 Low PCM DOUT SD13 DPI D17 - SPI1 SCLK GPCLK1
22 Low SD0 CLK SD14 DPI D18 SD1 CLK ARM TRST -
23 Low SD0 CMD SD15 DPI D19 SD1 CMD ARM RTCK -
24 Low SD0 DAT0 SD16 DPI D20 SD1 DAT0 ARM TDO -
25 Low SD0 DAT1 SD17 DPI D21 SD1 DAT1 ARM TCK -
26 Low SD0 DAT2 TE0 DPI D22 SD1 DAT2 ARM TDI -
27 Low SD0 DAT3 TE1 DPI D23 SD1 DAT3 ARM TMS -
Table 9: GPIO Bank0 Alternate Functions
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Default
GPIO Pull ALT0 ALT1 ALT2 ALT3 ALT4 ALT5
28 None SDA0 SA5 PCM CLK FL0 - -
29 None SCL0 SA4 PCM FS FL1 - -
30 Low TE0 SA3 PCM DIN CTS0 - CTS1
31 Low FL0 SA2 PCM DOUT RTS0 - RTS1
32 Low GPCLK0 SA1 RING OCLK TXD0 - TXD1
33 Low FL1 SA0 TE1 RXD0 - RXD1
34 High GPCLK0 SOE N TE2 SD1 CLK - -
35 High SPI0 CE1 N SWE N - SD1 CMD - -
36 High SPI0 CE0 N SD0 TXD0 SD1 DAT0 - -
37 Low SPI0 MISO SD1 RXD0 SD1 DAT1 - -
38 Low SPI0 MOSI SD2 RTS0 SD1 DAT2 - -
39 Low SPI0 SCLK SD3 CTS0 SD1 DAT3 - -
40 Low PWM0 SD4 - SD1 DAT4 SPI2 MISO TXD1
41 Low PWM1 SD5 TE0 SD1 DAT5 SPI2 MOSI RXD1
42 Low GPCLK1 SD6 TE1 SD1 DAT6 SPI2 SCLK RTS1
43 Low GPCLK2 SD7 TE2 SD1 DAT7 SPI2 CE0 N CTS1
44 None GPCLK1 SDA0 SDA1 TE0 SPI2 CE1 N -
45 None PWM1 SCL0 SCL1 TE1 SPI2 CE2 N -
Table 10: GPIO Bank1 Alternate Functions
Table 9 and Table 10 detail the default pin pull state and available alternate GPIO functions. Most of
these alternate peripheral functions are described in detail in the Broadcom Peripherals Specification
document and have Linux drivers available.
9.1.2 Secondary Memory Interface (SMI)
The SMI peripheral is an asynchronous NAND type bus supporting Intel mode80 type transfers at 8 or
16 bit widths and available in the ALT1 positions on GPIO banks 0 and 1 (see Table 9 and Table 10). It
is not publicly documented in the Broadcom Peripherals Specification but a Linux driver is available in
the Raspberry Pi Github Linux repository (bcm2835 smi.c in linux/drivers/misc).
9.1.3 Display Parallel Interface (DPI)
A standard parallel RGB (DPI) interface is available on bank 0 GPIOs. This up-to-24-bit parallel interface can support a secondary display. Again this interface is not documented in the Broadcom Peripherals Specification but documentation can be found here.
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9.1.4 SD/SDIO Interface
The BCM283x supports two SD card interfaces, SD0 and SD1.
The first (SD0) is a proprietary Broadcom controller that does not support SDIO and is the primary
interface used to boot and talk to the eMMC or SDX x signals.
The second interface (SD1) is standards compliant and can interface to SD, SDIO and eMMC devices;
for example on a Raspberry Pi 3 it is used to talk to the on-board BCM43438 WiFi device in SDIO
mode.
Both interfaces can support speeds up to 50MHz single ended (SD High Speed Mode).
9.2 CSI (MIPI Serial Camera)
Currently the CSI interface is not openly documented and only CSI camera sensors supported by the
official Raspberry Pi firmware will work with this interface. Supported sensors are the OmniVision
OV5647 and Sony IMX219.
It is recommended to attach other cameras via USB.
9.3 DSI (MIPI Serial Display)
Currently the DSI interface is not openly documented and only DSI displays supported by the official
Raspberry Pi firmware will work with this interface.
Displays can also be added via the parallel DPI interface which is available as a GPIO alternate function
- see Table 9 and Section 9.1.3
9.4 USB
The BCM283x USB port is On-The-Go (OTG) capable. If using either as a fixed slave or fixed master,
please tie the USB
The USB port (Pins USB DP and USB DM) must be routed as 90 ohm differential PCB traces.
Note that the port is capable of being used as a true OTG port however there is no official documentation.
Some users have had success making this work.
OTGID pin to ground.
9.5 HDMI
BCM283x supports HDMI V1.3a.
It is recommended that users follow a similar arrangement to the Compute Module IO Board circuitry
for HDMI output.
The HDMI CK P/N (clock) and D0-D2 P/N (data) pins must each be routed as matched length 100
ohm differential PCB traces. It is also important to make sure that each differential pair is closely phase
matched. Finally, keep HDMI traces well away from other noise sources and as short as possible.
Failure to observe these design rules is likely to result in EMC failure.
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9.6 Composite (TV Out)
The TVDAC pin can be used to output composite video (PAL or NTSC). Please route this signal away
from noise sources and use a 75 ohm PCB trace.
Note that the TV DAC is powered from the VDAC supply which must be a clean supply of 2.5-2.8V. It
is recommended users generate this supply from 3V3 using a low noise LDO.
If the TVDAC output is not used VDAC can be connected to 3V3, but it must be powered even if the
TV-out functionality is unused.
10 Thermals
The BCM283x SoC employs DVFS (Dynamic Voltage and Frequency Scaling) on the core voltage.
When the processor is idle (low CPU utilisation), it will reduce the core frequency and voltage to reduce
current draw and heat output. When the core utilisation exceeds a certain threshold the core votlage
is increased and the core frequency is boosted to the maximum working frerquency. The voltage and
frequency are throttled back when the CPU load reduces back to an ’idle’ level OR when the silicon
temperature as mesured by the on-chip temperature sensor exceeds 85C (thermal throttling).
A designer must pay careful attention to the thermal design of products using the CM3/CM3L so that
performance is not artificially curtailed due to the processor thermal throttling, as the Quad ARM complex in the BCM2837 can generate significant heat output.
10.1 Temperature Range
The operating temperature range of the module is set by the lowest maximum and highest minimum of
any of the components used.
The eMMC and LPDDR2 have the narrowest range, these are rated for -25 to +80 degrees Celsius.
Therefore the nominal range for the CM3 and CM3L is -25C to +80C.
However, this range is the maximum for the silicon die; therefore, users would have to take into account
the heat generated when in use and make sure this does not cause the temperature to exceed 80 degrees
Celsius.
11 Availability
Raspberry Pi guarantee availability of CM1, CM3 and CM3 Lite until at least January 2023.
12 Support
For support please see the hardware documentation section of the Raspberry Pi website and post questions to the Raspberry Pi forum.
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